As the device for recovering floating materials on the liquid surface, an arrangement based on a technique has been known in which a double float-type arrangement having not only a main float for floating and supporting a recovery device main body but also a gate float for retaining a gate portion is used, that is, an inflow hole of floating materials near a liquid surface, thereby attaining efficient recovery of floating materials floating on the liquid surface by allowing the floating materials to flow in and/or sucking them, etc.
In order to efficiently and reliably recover floating materials floating on the liquid surface such as scum and oil, it is desirable that the gate portion which is an inflow hole part of a recovery portion is always in a state of following the liquid surface.
a device for recovering floating materials on the liquid surface and
Where floating materials on the liquid surface are relatively small in diameter, they flow in the gate portion smoothly. However, where the floating materials are those of several millimeters or larger in diameter, they may be caught at a marginal part of the gate portion and cannot be recovered. And, if the gate portion is further lowered than a liquid level, the liquid-level floating materials are recovered in a greater quantity but at the same time water flows in a larger quantity. Thus, it is necessary to install a larger-capacity separator which separates the thus recovered scum and oil from water. This poses a problem.
Therefore, such a technique has been proposed that has a raking/gathering arrangement so that floating materials on the liquid surface flow in a gate portion efficiently by disposing a rotary blade-like raking/gathering unit around the gate portion or in the vicinity thereof, thereby allowing more floating materials on the liquid surface to flow in the gate portion without unnecessarily lowering the gate portion from the liquid surface (liquid level), (refer to Patent Document 1, for example).
Patent Document 1: Japan Patent Pre-Publication No. 2012-239951